Radio receiving apparatus



p 1942. I J'. J. ADAMS 2,295,191

RADIO RECEIVING APPARATUS Filed Sept. 19, 1940 2 Sheets-Sheet l INVENTOR.

J flab/72.5 281M A TORNEY.

p 1942- J. J. ADAMS RADIO RECEIVING APPARATUS 2 Sheets-Sheet 2 Filed Sept. 19, 1940 INVENTOZK.

A ORNEY.

Patented Sept. 8, 1942 UiTED STATES T, OFFICE RADIO RECEIVING APPARATUS James J. Adams, Chicago, Ill., assignor to Zenith Radio Corporation, Chicago, 111., a corporation of Illinois This invention relates to radio receiving apparatus, and more particularly concerns the construction and arrangement of the signal-receiving antenna and of the lead-in connection extending therefrom to the radio receiving set.

The principal object of the invention is to construct the signal-receiving antenna and the antenna lead-in of radio receiving apparatus and provide for their disposal and support within the casing of a radio receiving set so that the antenna may be conveniently removed for use outside of the casing and the lead-in extended to accommodate such outside use of the antenna, and so that they may be easily returned to their proper positions and arrangement for use within I the casing, the construction being such that the replacement of these parts within the casing by the user will be uniform, and their disposal with respect to each other and with respect to the elements with which they are connected and associated will be such as to preserve their proper operative relationship and participation in main-.

taining the radio receptive qualities of the apparatus as originally designed by the manufacturer.

While the invention is primarily designed for use with a compactly arranged portable radio receiving set, having a loop antenna which may be housed and used within the casing thereof or removed and individually supported apart therefrom without disconnecting the lead-in connecting it therewith, it is to be understood that the usefulness of the invention is not limited to portable receivers or to the particular form of antenna herein shown.

In the drawings- Figure l is a rear perspective view of a portable radio receiving set embodying my invention, showing the hinged back panel of the casing thereof in open position to disclose the arangement of the signal-receiving loop-antenna unit and of the lead-in connection when the antenna is to be used and/or carried about within the casing; v

Figure 2 is a front perspective view of the portable receiving set of Figure 1, showing theback panel of the casing in closed position, with the loop-antenna unit removed therefrom, ready to be individually supported apart from the set and 7 connected therewith by my improved lead-in;

Figure 3 is a vertical sectional view, upon an enlarged scale, taken upon the line 33 of Figure 1, showing in greater detail the compact arrangement of the loop-antenna unit and the lead-in when positioned and supported as in Figure 1;

Figure 4-is a fragmentary detail View of the lead-in when unfolded and extended; Figure 5 is a sectional view, taken upon the line E5 of Figure 4; and A Figure 6 is a view similar to Figure 5, showing the folded arrangement of the lead-in.

It is well known to those acquainted with the designing of radio circuits that the inductance, capacitance and resistance of the antenna, and of the antenna connecting leads, are important factors in the design of radio receiving apparatus. This is particularly true when the antenna is of the loop type, because such an antenna is an inductance unit and forms, with the connecting leads extending therefrom, part of a tuned circuit which is coupled to other tuned circuits of the apparatus. Consequently, variation in the intrinsic inductance, capacitance and resistance of the loop antenna and/or of its connecting leads varies the resonance characteristics, or tracking, of the antenna circuit with respect to said other tuned circuits and causes mis-alignment therewith. In other words, the greatest efficiency is obtainable when the tuning range of the antenna circuit tracks with, or is in alignment with, the tuning range of said other circuits.

In the single tuning control type of radio apparatus, if the antenna circuit, of which the antenna and antenna connecting leads are a part, is thrown out of alignment with the subsequent tuned circuits, the result is ineflicient operation, as it is impossible to correct the mis-alignment without the use of separately adjustable correcting means for said circuit, so that, if the single tuning control feature is to be retained, the misalignment must be prevented, rather than corrected, in order that the total possible signal output from the antenna circuit may be transmitted to the subsequent tuned circuits of the apparatus.

In portable radio receiving apparatus, the importance of an efficient antenna and of the maintainance of accurate alignment of the antenna circuit is probably at its highest. Because it is possible to obtainhigh signal output from the antenna circuit, if accurate alignment of said circuit maybe maintained in relation to the other tuned circuits, less power need be used and weight and overall dimensions may be reduced by the elimination of subsequent stages of amplification. These advantages are of great importance in portable apparatus where the operating power is often limited, and where it is usually desirable to have the apparatus light and compact. Furthermore, correct alignment and high signal output are essential in obtaining high selectivity, and all of these are important factors in obtaining a high rejection of what are known as image and ghost signals. Also, the maintenance of high output values in the antenna circuit in the manner hereinafter described results in a high signalto-internal-noise ratio.

It is therefore clear that, where efficiency of the antenna circuit becomes particularly important, it is highly desirable to maintain, as nearly as possible, the intrinsic resistance, capacitance, and inductance of the antenna circuit as known quantities.

It has been found desirable, both in portable apparatus and in other types of radio receiving apparatus, to use a loop antenna which may be placed within the case of the radio receiving apparatus or removed and placed anywhere within a given distance therefrom. To make this feasible, the antenna must be connected with the apparatus by a connecting lead-member of some length which must also be stowable within the case.

When the antenna and the antenna connecting lead are placed within the case of the radio receiving apparatus, the capacitance and inductance of the antenna circuit are affected by electrostatic and electro-magnetic interaction between the antenna and the antenna connecting lead and other objects (principally, the chassis of the apparatus). For example, the metal chassis affects the inductance of the antenna loop. Between all three units above named, capacitance interaction occurs. Capacitance is also present in the convolutions of the necessarily gathered together or bunched arrangement of the antenna connecting lead. As may be readily understood, the distance between the above mentioned units and the placement of each in relation to the others are important factors which govern the amount of capacitance and inductance to be found in the antenna circuit.

It is sometimes convenient to determine the inductance and capacitance of the antenna circuit by the placement of these units. If the several units could be kept in their original arrangement within the case, the tracking alignment of the antenna circuit would be maintained as originally designed. However, with the removable feature, there exists the constant likelihood of replacement of the units in different arrangement, seldom alike twice.

It is very difficult, even for an experienced operator, to replace the antenna and antenna connecting lead within the set just as they were when the radio receiving apparatus was originally aligned. Furthermore, those not familiar with the art do not take note of the original arrangement and do not even realize the necessity for accurate replacement of these two mentioned units.

My invention not only provides for the accurate and uniform replacement of the antenna and antenna connecting lead-member, but makes the accurate and uniform replacement thereof easier than any other method of replacement that the operator might try. As a result, the uniform and accurate replacement of these two units is assured.

One form of my invention is shown in the accompanying drawings, in which similar numerals refer to similar parts throughout the views. Referring particularly to Figure 1, reference numeral I is a portable radio receiving apparatus with a hinged back 2 included therein. Reference numeral 3 indicates the chassis of said portable apparatus. Reference numeral 4 indicates a loop antenna, including the supporting frame therefor and the suction-cup supporting members, all of which are hereinafter collective- 1y referred to as the loop antenna. Reference numeral 5 indicates the antenna connecting leadmember. Reference numerals 6 and I are the lead wires carried in the connecting lead-member 5. 8 and 9 are respectively collars and latch members which serve as guides and retaining means for the placement and securing of the loop antenna 4 in the predetermined position. Collars 8 and latches 9 are secured to the panel ID by screws I I and are revolvable about said screws. Reference numerals I2 and I3 are parallel supporting guide-blocks for the antenna connecting lead-member 5. Latch I4 is mounted on block I2 by screw I5.

In order to fix the spacing of the leads 6 and 1, said leads are sewed to the outer edges of a relatively stiff strip of canvas or webbing constituting the connecting lead-member 5, as shown in Figure 4. As may be readily understood, a connecting lead-member, such as 5, would need to be gathered or bunched together in some manner in order to be stowed within the casing of the apparatus. To maintain accurate uniformity in the folding and replacing of the connecting lead 5, a pre-creased fold is made at such points across the member 5 as indicated by I6 in Figures 2, 4, 5 and 6.

The formation of the folds is shown in detail in Figures 4, 5 and 6. The connecting leadmember 5 is folded back and forth upon itself at the points I! and stitched across through the folds, thus holding the folding points permanent and predetermining the form in which the leadmember will always be stowed.

Assuming that the loop antenna is in the position shown in Figure 2, the replacement would be as follows: opening the hinged back 2, placing the loop antenna upon the collars 8 and against the panel II), as shown in Figures 1 and 3, and closing the latches 9. Then folding together the connecting lead 5 which tends to fold at the creased folding points I I, placing the folded connecting lead 5 between the guide members I2 and I3 and then turning the latch I4 into the position shown in Figure 1. When the hinged back is again closed, the distance and placement of the three units are in the same relative arrangement as when the apparatus was originally constructed.

Having fully described my invention and the manner of its use, I claim- 1. In radio receiving apparatus, a casing therefor, an antenna removably arranged within said casing and positionable apart therefrom, means comprised in said casing removably supporting said antenna in a predetermined position, an an tenna lead connecting said antenna with said apparatus, said antenna lead being extensible to accommodate the positioning of said antenna apart from said casing and collapsible for positioning with said antenna within said casing, means fixed within said casing removably supporting said antenna lead in a position predetermined with respect to said antenna, and means comprised in the structure of said antenna lead acting thereupon to effect a uniform arrangement thereof as it is collapsed.

2. In radio receiving apparatus, a casing therefor, an antenna removably arranged within said casing and positionable apart therefrom, means comprised in said casing removably supporting said antenna in a predetermined position, an an-jv tenna lead connecting said antenna with said apv paratus, said antenna lead being extensible to accommodate the positioning of said antenna apart from said casing and collapsible for positioning with said antenna within said casing, 

